package com.imooc.course.server.utils;

import org.springframework.web.multipart.MultipartFile;

import java.io.*;
import java.util.Base64;

public class Base64ToMultipartFile implements MultipartFile {

    private final byte[] imgContent;
    private final String header;

    public Base64ToMultipartFile(byte[] imgContent, String header) {
        this.imgContent = imgContent;
        this.header = header.split(";")[0];
    }

    @Override
    public String getName() {
        // TODO - implementation depends on your requirements
        return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
    }

    @Override
    public String getOriginalFilename() {
        // TODO - implementation depends on your requirements
        return System.currentTimeMillis() + (int) Math.random() * 10000 + "." + header.split("/")[1];
    }

    @Override
    public String getContentType() {
        // TODO - implementation depends on your requirements
        return header.split(":")[1];
    }

    @Override
    public boolean isEmpty() {
        return imgContent == null || imgContent.length == 0;
    }

    @Override
    public long getSize() {
        return imgContent.length;
    }

    @Override
    public byte[] getBytes() throws IOException {
        return imgContent;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(imgContent);
    }

    @Override
    public void transferTo(File dest) throws IOException, IllegalStateException {
        new FileOutputStream(dest).write(imgContent);
    }

    public static MultipartFile base64ToMultipart(String base64) {
        String[] baseStrs = base64.split(",");


        Base64.Decoder decoder1 = Base64.getDecoder();
        byte[] bytes = decoder1.decode(baseStrs[1]);

//BASE64Decoder是Oracle 1.8的解密类，OpenJDK没有，所以用Base64.getDecoder()代替
//            BASE64Decoder decoder = new BASE64Decoder();
//            byte[] b = new byte[0];
//            b = decoder.decodeBuffer(baseStrs[1]);

        for(int i = 0; i < bytes.length; ++i) {
            if (bytes[i] < 0) {
                bytes[i] += 256;
            }
        }

        return new Base64ToMultipartFile(bytes, baseStrs[0]);
    }
}